The usual method of investigating dermatographism (D), which is typically white in atopic eczema (AE), allows only a qualitative rating. To allow reproducible quantification of D we have developed an easily usable device termed Dermography. This can be fitted with one to three blunt tapered metal bars of different weight applying a constant stretching pressure over the whole skin area to be examined with different pressures at isolated lines. We used this device to study D in 27 patients with AE and in 20 healthy controls. Of the 27 patients, 21 had white D, 2 had red D, and 4 none at each pressure applied. In 18 of the 20 controls D was red. Both groups differed significantly with regard to the time until the onset of D and its duration, the former being prolonged and the latter shortened in patients with AE. Simultaneous and constant application of distinct grades of pressure for quantitative dermographometry is a method than can reliably be used for the study of inter- and intraindividual variations in vascular reactivity.